Characterization of membrane structures regulating primary ciliogenesis by quantitative isotropic ultrastructure imaging.

The trafficking, docking, and fusion of membrane vesicles at the mother centriole (MC) are required to construct the primary cilium. Here, we determined the three-dimensional (3D) membrane ultrastructures, and associated proteins, involved in primary cilium assembly upstream of axoneme growth. Our work reveals that the enlargement of small vesicles docked to the MC is a key trigger for ciliogenesis progression, a process requiring the MC distal appendage protein CEP164.

Coordination of IFT20 With Other IFT Components Is Required for Ciliogenesis.

Background: Primary cilia are organelles formed on the cell surface. They can act as cellular antennae to sense signals and play important roles in various biological processes. Abnormalities in primary cilia lead to a variety of diseases collectively known as ciliopathies.

TBC1D20 coordinates vesicle transport and actin remodeling to regulate ciliogenesis.

TBC1D20 deficiency causes Warburg Micro Syndrome in humans, characterized by multiple eye abnormalities, severe intellectual disability, and abnormal sexual development, but the molecular mechanisms remain unknown. Here, we identify TBC1D20 as a novel Rab11 GTPase-activating protein that coordinates vesicle transport and actin remodeling to regulate ciliogenesis. Depletion of TBC1D20 promotes Rab11 vesicle accumulation and actin deconstruction around the centrosome, facilitating the initiation of ciliogenesis even in cycling cells.

Proliferation associated 2G4 is required for the ciliation of vertebrate motile cilia.

Motile cilia are critical structures that regulate early embryonic development and tissue homeostasis through synchronized ciliary motility. The formation of motile cilia is dependent on precisely controlled sequential processes including the generation, migration, and docking of centrioles/basal bodies as well as ciliary growth. Using the published proteomics data from various organisms, we identified proliferation-associated 2G4 as a novel regulator of ciliogenesis.

An alternative cell cycle coordinates multiciliated cell differentiation.

The canonical mitotic cell cycle coordinates DNA replication, centriole duplication and cytokinesis to generate two cells from one. Some cells, such as mammalian trophoblast giant cells, use cell cycle variants like the endocycle to bypass mitosis. Differentiating multiciliated cells, found in the mammalian airway, brain ventricles and reproductive tract, are post-mitotic but generate hundreds of centrioles, each of which matures into a basal body and nucleates a motile cilium.

Exploring the potential prompting role of cervical human papilloma virus detection in vulvar lesions: a cross-sectional study in China.

Introduction: The etiology and clinical presentation of vulvar carcinomas, especially vulvar lesions, are not fully understood. Because the vulva and cervix are anatomically connected, human papillomavirus (HPV) is the main cause of cervical lesions. Thus, this study explored the potential characteristics and effects of specific HPV infection types across vulvar lesions and concurrent cervical lesions.

Dynamic changes of endothelial and stromal cilia are required for the maintenance of corneal homeostasis.

Primary cilia are distributed extensively within the corneal epithelium and endothelium. However, the presence of cilia in the corneal stroma and the dynamic changes and roles of endothelial and stromal cilia in corneal homeostasis remain largely unknown. Here, we present compelling evidence for the presence of primary cilia in the corneal stroma, both in vivo and in vitro.

Multi-color live-cell fluorescence imaging of primary ciliary membrane assembly and dynamics.

The ciliary membrane is continuous with the plasma membrane but has distinct lipid and protein composition, which is key to defining the function of the primary cilium. Ciliary membranes dynamically assemble and disassemble in association with the cell cycle and directly transmit signals and molecules through budding membranes. Various imaging approaches have greatly advanced the understanding of the ciliary membrane function.

Male infertility-associated Ccdc108 regulates multiciliogenesis via the intraflagellar transport machinery.

Motile cilia on the cell surface generate movement and directional fluid flow that is crucial for various biological processes. Dysfunction of these cilia causes human diseases such as sinopulmonary disease and infertility. Here, we show that Ccdc108, a protein linked to male infertility, has an evolutionarily conserved requirement in motile multiciliation.

CLEM Characterization of Rab8 and Associated Membrane Trafficking Regulators at Primary Cilium Structures.

Correlative light and electron microscopy (CLEM) enables determination of high-resolution structural information for proteins of interest within their biological context through the combination of electron and fluorescence microscopies. Numerous electron microscopy (EM) studies of primary cilia have provided ultrastructural details about these antennal-like organelles that extend from the surface of the cell. The core structure of the cilium includes a microtubule-based axoneme, a basal body derived from the mother centriole, and the ciliary membrane, which is connected to the plasma membrane.

A ciliopathy complex builds distal appendages to initiate ciliogenesis.

Cells inherit two centrioles, the older of which is uniquely capable of generating a cilium. Using proteomics and superresolved imaging, we identify a module that we term DISCO (distal centriole complex). The DISCO components CEP90, MNR, and OFD1 underlie human ciliopathies.

Live-cell fluorescence imaging of ciliary dynamics.

The cilium was one of the first organelles observed through a microscope. Motile cilia appear as oscillating cell appendages and have long been recognized to function in cell motility. In contrast, the far more widespread non-motile cilia, termed primary cilia, were thought to be vestigial and largely ignored following their initial description over a century ago.

RAB19 Directs Cortical Remodeling and Membrane Growth for Primary Ciliogenesis.

Primary cilia are sensory organelles that utilize the compartmentalization of membrane and cytoplasm to communicate signaling events, and yet, how the formation of a cilium is coordinated with reorganization of the cortical membrane and cytoskeleton is unclear. Using polarized epithelia, we find that cortical actin clearing and apical membrane partitioning occur where the centrosome resides at the cell surface prior to ciliation. RAB19, a previously uncharacterized RAB, associates with the RAB-GAP TBC1D4 and the HOPS-tethering complex to coordinate cortical clearing and ciliary membrane growth, which is essential for ciliogenesis.

Akt Regulates a Rab11-Effector Switch Required for Ciliogenesis.

Serum starvation stimulates cilia growth in cultured cells, yet serum factors associated with ciliogenesis are unknown. Previously, we showed that starvation induces rapid Rab11-dependent vesicular trafficking of Rabin8, a Rab8 guanine-nucleotide exchange factor (GEF), to the mother centriole, leading to Rab8 activation and cilium growth. Here, we demonstrate that through the LPA receptor 1 (LPAR1), serum lysophosphatidic acid (LPA) inhibits Rab11a-Rabin8 interaction and ciliogenesis.

Publisher Correction: Investigation of F-BAR domain PACSIN proteins uncovers membrane tubulation function in cilia assembly and transport.

In the original version of this Article, the fifth sentence of the abstract incorrectly read 'Remarkably, we show that PACSIN1 and EHD1 assemble membrane t7ubules from the developing intracellular cilium that attach to the plasma membrane, creating an extracellular membrane channel (EMC) to the outside of the cell.', and should have read 'Remarkably, we show that PACSIN1 and EHD1 assemble membrane tubules from the developing intracellular cilium that attach to the plasma membrane, creating an extracellular membrane channel (EMC) to the outside of the cell.'.

Investigation of F-BAR domain PACSIN proteins uncovers membrane tubulation function in cilia assembly and transport.

The intracellular ciliogenesis pathway requires membrane trafficking, fusion, and reorganization. Here, we demonstrate in human cells and zebrafish that the F-BAR domain containing proteins PACSIN1 and -2 play an essential role in ciliogenesis, similar to their binding partner and membrane reorganizer EHD1. In mature cilia, PACSINs and EHDs are dynamically localized to the ciliary pocket membrane (CPM) and transported away from this structure on membrane tubules along with proteins that exit the cilium.

Primary Cilium-Mediated Retinal Pigment Epithelium Maturation Is Disrupted in Ciliopathy Patient Cells.

Primary cilia are sensory organelles that protrude from the cell membrane. Defects in the primary cilium cause ciliopathy disorders, with retinal degeneration as a prominent phenotype. Here, we demonstrate that the retinal pigment epithelium (RPE), essential for photoreceptor development and function, requires a functional primary cilium for complete maturation and that RPE maturation defects in ciliopathies precede photoreceptor degeneration.

In Vitro Modeling Using Ciliopathy-Patient-Derived Cells Reveals Distinct Cilia Dysfunctions Caused by CEP290 Mutations.

Mutations in CEP290, a transition zone protein in primary cilia, cause diverse ciliopathies, including Leber congenital amaurosis (LCA) and Joubert-syndrome and related disorders (JSRD). We examined cilia biogenesis and function in cells derived from CEP290-LCA and CEP290-JSRD patients. CEP290 protein was reduced in LCA fibroblasts with no detectable impact on cilia; however, optic cups derived from induced pluripotent stem cells (iPSCs) of CEP290-LCA patients displayed less developed photoreceptor cilia.

Chromatin-bound NLS proteins recruit membrane vesicles and nucleoporins for nuclear envelope assembly via importin-α/β.

The mechanism for nuclear envelope (NE) assembly is not fully understood. Importin-β and the small GTPase Ran have been implicated in the spatial regulation of NE assembly process. Here we report that chromatin-bound NLS (nuclear localization sequence) proteins provide docking sites for the NE precursor membrane vesicles and nucleoporins via importin-α and -β during NE assembly in Xenopus egg extracts.

Ultrastructural remodelling of Ca(2+) signalling apparatus in failing heart cells.

Aims: The contraction of a heart cell is controlled by Ca(2+)-induced Ca(2+) release between L-type Ca(2+) channels (LCCs) in the cell membrane/T-tubules (TTs) and ryanodine receptors (RyRs) in the junctional sarcoplasmic reticulum (SR). During heart failure, LCC-RyR signalling becomes defective. The purpose of the present study was to reveal the ultrastructural mechanism underlying the defective LCC-RyR signalling and contractility.

AtFH8 is involved in root development under effect of low-dose latrunculin B in dividing cells.

Formins have been paid much attention for their potent nucleating activity. However, the connection between the in vivo functions of AtFHs (Arabidopsis thaliana formin homologs) and their effects on actin organization is poorly understood. In this study, we characterized the bundling activity of AtFH8 in vitro and in vivo.